Water Gardening: Pathway to Paradise or Plant Invasion?

Water Gardening: Pathway to Paradise or Plant Invasion?

The Popularity of Water Gardening is Steadily Increasing The number of U.S. households engaged in water gardening has jumped from 4 to 16 million in the last 5 yrs. Water gardening retail sales reached $1.56 billion in 2003

Water Gardens Are Versatile inside or outside large or small formal or informal

Aquatic Plants are Beneficial and Beautiful

Response to Market Demands Aquatic plants and/or water garden supplies now widely available through: nurseries and garden centers hardware/home center chains mail order catalogues internet sites

12 Popular Water Garden Plants of Concern Cabomba caroliniana (fanwort) Egeria densa (Brazilian waterweed) Eichhornia crassipes (water hyacinth) Hydrilla verticillata (hydrilla) Iris pseudacorus (yellow flag iris) Lythrum salicaria (purple loosestrife) Myriophyllum aquaticum (parrot-feather) Myriophyllum spicatum (Eurasian watermilfoil) Nymphoides peltata (yellow floating heart) Pistia statiotes (water lettuce) Salvinia molesta (giant salvinia) Trapa natans (water chestnut)

Cabomba caroliniana (fanwort) sold for aquariums and ornamental ponds native to southeastern U.S. spreads by stem fragments, seeds and roots

Egeria densa (Brazilian waterweed) native to eastern South America sold for aquariums and ornamental ponds earliest record in U.S. from NY in 1893 has been in Delta for several decades

Eichhornia crassipes (water hyacinth) native to tropical South America (Brazil) know to exist in CA since 1904 frequently sold for ornamental ponds dubbed world s worst aquatic weed

Hydrilla verticillata (hydrilla) native to warm regions of Asia introduced to FL in 1958 as an aquarium plant has spread to all continents except Antarctica came to CA as contaminant in aquatic nursery stock

Iris pseudacorus (yellow flag iris) native to Europe grown as an ornamental escaped cultivation reproduces by seed and creeping rhizomes

Lythrum salicaria (purple loosestrife) native to Eurasia grown as an ornamental escaped cultivation 2 million viable seeds per large plant spread to nearly all states in U.S. and Canada

Myriophyllum aquaticum (parrot-feather) native to South America earliest specimen collected from NJ in 1890 can survive freezing conditions

Myriophyllum spicatum (Eurasian watermilfoil) native to Europe and Asia sold for aquariums and ornamental ponds has spread to at least 45 states and Canada

Nymphoides peltata (yellow floating heart) native to Europe grown as an ornamental since at least 1882 spread by seed, rhizomes and fragments

Pistia stratiotes (water lettuce) native to tropical South America sold for ornamental ponds and aquariums free-floating; spreads by offsets and seeds

Salvinia molesta (giant salvinia) aquatic fern native to tropical South America plants can double biomass in 2-3 days sold as an aquatic ornamental spreads through stem fragmentation

Trapa natans (water chestnut) native to Europe, Asia and Africa introduced in late 1800s as a pond ornamental has woody, nut-like seeds with barbed spines

Hyacinth and Egeria Control in the Delta DBW program implemented in 1987 (hyacinth) and 2001 (egeria) over $45 million spent on control - management continues annually

CDFA Aquatic Plant Control hydrilla giant salvinia alligatorweed The California Dept. of Food and Agriculture has spent over $35 million on aquatic weed control since the 1970s -- mostly on hydrilla eradication purple loosestrife

Movement of Aquatic Plants Through the Horticultural Trade in s. New England 76% of non-native aquatic plants are escapes from cultivation (Les and Mehrhoff, 1999) in NZ 75% of aquatic invasive plants are of horticultural origin (Champion and Clayton, 2000) the 1 st monoecious hydrilla in CA was traced to a contaminated lily shipment

Findings of Maki and Galatowitsch, 2003 92% - Fed. Noxious Weeds acquired 93% - plant/animal not requested 18% - misidentified plants 43% - unordered seeds plants received but not ordered: purple loosestrife, hydrilla, giant salvinia, curly-leaf PW aquatic inverts found in 30 of 40 plant orders; fish found in two orders

Invasive Aquatic Plants Available on the Internet water lettuce 85% parrot feather 80% water hyacinth 70% egeria 65% fanwort/yf Iris 55% yellow floating heart 50% salvinia 35% milfoil 25% purple loosestrife 5% hydrilla/chestnut 0%

Education, Education, Education There is a correlation between familiarity w/ issue and a preference NOT to buy invasive plants (Reichard and White 2001). work with media & publishers reach bigger and broader audiences -Botanical Gardens - Master Gardeners - Garden Clubs

What Can Water Gardeners Do to Help? DO NOT RELEASE plants near or into a water body Build your water garden away from natural waterways Site your pond away from areas that flood Learn which plants are likely to be invasive Request non-invasive plants from your nursery Inspect your plant purchases for hitchhikers

Role of a Responsive Nursery Know which species are regionally/federally regulated Abide by all laws governing plant importation, sale, etc. Verify the scientific name of what you purchase Inspect shipments to make sure they are not contaminated Educate staff/customers promote Don t Release message Provide a selection of non-invasive plants for consumers

A New National Campaign Habitattitude: The message is DON T RELEASE www.habitattitude.net

RIDNIS Project Reducing the Introduction and Distribution of Non-native Aquatic Invasive Species Through Outreach and Education develop Best Practice Guidelines with industry produce outreach materials in Spanish & Chinese publish articles in trade magazines partner with others http://www.ridnis.ucdavis.edu

Thank you!